Magneto-electric ignition machine



Feb. 23 1926.,

W. HAHNLE MAGNETO ELECTRIC IGNITION MACHINE Filed Oct. 27. 1921 Patented Feb. 23, 1926.

UNITED STATES 1,574,646 PATENT OFFICE.

WALTER HBHNLE, OF STUTTGART-DEGERLOCH, GERMANY, ASSIGNOR TO ROBERT BOSCH .AKTIENGESELLSCHAFT, OF STUTTGAR-T, GERMANY.

MAGNETO-ELECTRIC IGNITION MACHINE.

Application filed October 27, 1921. Serial No. 510,981.

To all whom it may concern:

Be it known that I, IVALTER HAHNLE, a citizen of Germany, and residing at Stuttgart-Degerloch, Germany, have invented certain new and useful Improvements in Magneto-Electric Ignition Machines, of which the following is a specification.

l/Vith magneto-electric ignition machines the currents induced in the armature winding produce a magnetic field, the so-called armature field, which is in opposite direction to the field of the permanent poles. The magnets are weakened by the armature field whereby the electric efficiency of the ignition machine is diminished. It is already known to diminish the influence or the armature field by providing for its lines of force, by special conducting pieces, a way outside of the magnet poles, the arrangement being such that the lines of force may close the magnetic circuit in order to be deflected off the magnet poles. 'These known arrangements necessitate, however, a material enlargement of the machine and cannot be em ployed for some kinds of ignition apparatus for instance those in which a rotary sleeve is arranged between the magnet pole shoes and the armature or in which the magnet rotates.

Now, according to this invention, a magnectic shunt for the lines of force of the armature field away from the magnet is produced by a special configuration of the magnet pole-shoes themselves, the arrangement being such that the opposed ends of the magnet pole shoes are approached towards each other to such a measure as to provide thereover and through the intervening air gap, a path for lines of force of the armature field, the magnetic resistance of which is greater than the resistance of the main path between the poles of the magnet over the armature core together with the double air gap between the armature and thepole-shoes but is not greater than that of the magnet itself.

In order to make my invention more clear, I refer to the accompanying drawing, which shows diagrammatically one form of construction of a'magneto-electric ignition machine having pole-shoes of the above men tioned improved kind. In this figure E1? is the armature of the ignition apparatus; it rotates between pole-shoes b, b which are arranged in known mannerbetween the legs dotted line the armature flux.

of a horseshoe magnet. The ends of the pole-shoes are prolonged to approach each other so as to produce a small gap, the dimensions of which are such that the magnetic resistance of the shunt is, indeed, greater than the resistance of the main way formed by the armature core together with the double air gap between the armature and the magnet pole-shoes, but is, on the other hand, not greater than the resistance of the magnet itself. In the figure the dashed line indicates the exciting flux and the dashed and AS shown, the shoes A of the armature are much shorter than the pole-shoes b, I; of the mag- 1' ct. In the present case each armature-shoe occupies about one-half the length of each pole-shoe, or about one-quarter of the circumference of the armature. These relative lengths of the shoes of the magnet and of the armature lead to such rates of variation of the magnetic flux passing through the armature-coil or winding as will produce the necessary voltage at the proper position of the armature for effective spark-production in the engine cylinder.

The invention may be employed in connection with all kinds of ignition machines, especially those with rotating magnets and those with rotating conducting pieces provided for the lines of force, and arranged between the armature and the pole-shoes. In the latter case the distance of the conducting pieces from each other must be determined in conformity with this invention. The pole-shoes might also be provided with special lugs which may be approached towards each other until the proper distance, as before mentioned, is reached.

A secondary advantage attained by that approachment consists in the magnet being always closed also if the armature (for instance because of a repair) is removed from the machine, whereby the otherwise arising 100 demagnetization of the magnet is prevented.

Having now described my invention, what I claim as new and desire to secure by Letters Patent of the United States is: 105

1. A magneto-electric ignition device comprising, in combination, a magnet, poleshoes formed on said magnet and having opposed arcuate surfaces, an armature arranged to be excited by said magnet, said 9 armature having shoes with arcuate surfaces, the arcs of which are of less extent than the arcs of said pole-shoes, said pole shoes having opposed prolongations to form a reduced air-gap between the ends of said pole-shoes, the magnetic resistance of which is such that the magnetic resistance over said pole-shoes and through said air-gap is greater than the magnetic resistance over said pole-shoes and said armature, but is not greater than the magnetic resistance of the magnet itself.

2. A 'magneto-eleetric generator having a magnet formed with ooposed pole-shoes and an armature arrange to be excited by the magnet, said magnet aole-shoes having opposed prolongations 0 such close approach as to provide over said opposed prolongations and through the intervening air-gap a shunt path for lines of force of a magnetic resistance greater than the magnetic resistance of the main path between netic resistance of the main path between the poles of the magnet over said armature and through the air-gaps between the armature and the pole-shoes, but not greater than the magnetic resistance of the magnet itself, the shoes of the armature being substantially less in length than the said mag net pole-shoes.

4. A magneto-electric ignition device comprising in combination, a magnet, pole shoes attached to said magnet having opposed arcuate surfaces, an armature between said pole shoes, said armature hav ing shoes with arcuate surfaces, the arcs of which are of less extent than the arcs of said pole shoes, said pole shoes having opposed prolongations to form a reduced air gap between the ends of said pole shoes the magnetic resistance of which is such that the magnetic resistance over said pole shoes and through said air gap is greater than the magnetic resistance over said pole shoes and said armature, but is not greater than the resistance of the magnet itself.

5. A magneto-electric generator of the bobbin type having opposed magnet pole shoes and an armature rotatable therebetween, said magnet pole shoes having opposed extensions of such close approach as to provide over said opposed extensions and through the intervening air gap a shunt path for lines of force of a magnetic resistance greater than the magnetic resistance of the main path between the poles of the magnet of the generator over said armature and through the air gaps between the armature heads and pole shoes but not greater than the resistance of said magnet itself.

In testimony whereof I have affixed my signature.

WALTER HAHNLE. 

